Flat extrusion



FIG. 1 is a top view of the flat extrusion embodying my new design;

FIG. 2 is a bottom view thereof;

FIG. 3 is a left view thereof;

FIG. 4 is a right view thereof;

FIG. 5 is a front view thereof;

FIG. 6 is a back view thereof;

FIG. 7 is a left perspective view thereof; and,

FIG. 8 is a right perspective view thereof. 

The ornamental design for a flat extrusion, as shown and described. 